WO2018056093A1 - Optical fiber unit and optical fiber cable - Google Patents

Abstract

Provided is an optical fiber unit provided with a plurality of optical fibers and at least two bundling members for bundling the plurality of optical fibers, wherein: the two bundling members are wrapped around the plurality of optical fibers in an SZ shape and have adhering parts formed for adhering to each other at each reversing part; and the adhering parts include a plurality of intersections of the center lines of the two bundling members with each other.

Description

Optical fiber unit and optical fiber cable

The present invention relates to an optical fiber unit and an optical fiber cable.
This application claims priority on September 20, 2016 based on Japanese Patent Application No. 2016-183490 for which it applied to Japan, and uses the content for it here.

Conventionally, as disclosed in Patent Document 1, an optical fiber unit in which a binding material is wound around a plurality of optical fiber core wires or optical fiber strands (hereinafter simply referred to as optical fibers) is known. In this optical fiber unit, it is possible to improve the discriminability between the plurality of optical fiber units depending on the color of the binding material while suppressing the bundle of optical fiber cores from being scattered by winding the binding material.
Further, Patent Document 2 below proposes an optical fiber unit in which a plurality of binding materials are wound around a bundle of optical fibers in an SZ shape, and two binding materials are bonded at a reversal point in the winding direction. According to this configuration, when the part to which the two binding materials are bonded is peeled, the binding around the peeled part is released and the binding in the other part is maintained. Thereby, workability | operativity, such as an intermediate | middle post branch work of an optical fiber unit, can be made favorable.

Japanese Unexamined Patent Publication No. 2010-26196 Japanese Unexamined Patent Publication No. 2012-88454

By the way, in the optical fiber unit described in the above-mentioned patent document 2, since the reversal portions of the binding material are bonded to each other, the bonded state is likely to become unstable due to the unexpected peeling of the bonding portion.

The present invention has been made in view of such circumstances, and an object thereof is to stabilize the binding state of a binding material wound around a plurality of optical fibers in an SZ shape.

In order to solve the above problems, an optical fiber unit according to a first aspect of the present invention is an optical fiber unit comprising a plurality of optical fibers and at least two binding materials for binding the plurality of optical fibers. The two binding materials are wound around the plurality of optical fibers in an SZ shape, and form an adhesive portion that is bonded to each other at each reversal portion, and the adhesive portion has a center of the two binding materials. Multiple intersections between lines are included.

According to the optical fiber unit according to the first aspect, at the time of manufacturing the optical fiber unit, for example, the position where the reversal part of each binding material is formed and the shape of the reversal part varies, Two binding materials are stacked on each other to a sufficient extent. For this reason, it becomes possible to form an adhesion part reliably, and the binding state of a binding material can be stabilized.

The optical fiber unit according to a second aspect of the present invention is the optical fiber unit according to the first aspect, wherein the adhesive portion includes a plurality of adhesive surfaces on which the binding materials overlap, Adhesive surfaces are arranged at intervals in the longitudinal direction in which the optical fiber unit extends.

According to the second aspect, for example, when a force that separates the binding materials acts on the entire bonding portion, the external force can be received by the entire plurality of bonding surfaces. Therefore, it can suppress that an adhesion part peels unexpectedly. On the other hand, when the optical fiber is taken out by peeling off the adhesive portion, for example, the adhesive surface can be easily peeled by concentrating the force for separating the binding materials on one adhesive surface. Then, by sequentially peeling the bonding surface along the longitudinal direction, the bonding portion can be peeled with a small operating force, and the intermediate post-branching operation and the like can be facilitated.

In the optical fiber unit according to the third aspect of the present invention, in the optical fiber unit according to the second aspect, a gap is formed between the plurality of bonding surfaces and between the two binding materials. ing.

According to the third aspect, the gap between the two binding materials is formed between the bonding surfaces, and for example, the position where the reversal portion of the binding material is formed and the shape of the reversal portion vary. Even if it is a case, it is suppressed that the area of an adhesion surface changes greatly. Thereby, the intensity | strength of an adhesion part can be stabilized easily at the time of manufacture of an optical fiber unit.

The optical fiber unit according to a fourth aspect of the present invention is the optical fiber unit according to any one of the first to third aspects, wherein the adhesive portion has an intersection of two center lines of the binding material. 4 or more are included.

According to the fourth aspect, the length of the bonded portion in the longitudinal direction is ensured, and the binding state of the binding material can be further stabilized.

An optical fiber unit according to a fifth aspect of the present invention is the optical fiber unit according to any one of the first to fourth aspects, wherein the adhesive length L of the adhesive portion in the longitudinal direction in which the optical fiber extends, The binding pitch P of the binding material in the longitudinal direction satisfies 0.24 ≦ L / (P / 2) ≦ 0.8.

According to the fifth aspect, by setting the value of L / (P / 2) to 0.24 or more, the length in the longitudinal direction of the bonded portion occupying the entire binding material is secured, and the bonded portion is unexpected. Can be prevented from peeling off. Furthermore, when the value of L / (P / 2) is set to 0.8 or less, when manufacturing an optical fiber unit, the distance or time in the longitudinal direction from when the bonded portion is formed to when the binding material is reversed. Generation | occurrence | production of the adhesion failure resulting from being short can be suppressed.

The optical fiber unit according to a sixth aspect of the present invention is the optical fiber unit according to any one of the first to fifth aspects, wherein the adhesive strength of the adhesive portion is 11.6 gf or more and 95.2 gf or less. It is.

According to the sixth aspect, by making the adhesive strength of the adhesive portion 11.6 gf or more, it is possible to prevent the adhesive portion from being unexpectedly separated. Furthermore, the workability | operativity at the time of peeling binding materials in an adhesion part can be made favorable by the adhesive strength of an adhesion part being 95.2 gf or less.

An optical fiber unit according to a seventh aspect of the present invention is the optical fiber unit according to any one of the first to sixth aspects, wherein the overlap ratio of the two binding materials is greater than 100%, and 125% or less.

According to the seventh aspect, by making the overlapping rate of the binding material greater than 100%, the bonding surface between the binding materials can be reliably formed and the binding state can be stabilized. Furthermore, by setting the overlap rate to 125% or less, the area of the bonding surface can be secured and the bonding strength can be increased.

An optical fiber cable according to an eighth aspect of the present invention includes the optical fiber unit according to any one of the first to seventh aspects, and a sheath that covers the optical fiber unit.

According to the optical fiber cable according to the eighth aspect, the binding material is wound around the plurality of optical fibers in an SZ shape, and the binding state of the binding material is stable. For this reason, it is suppressed that the bundle of optical fibers is separated, the discrimination between the optical fiber units is ensured, and the workability such as the intermediate post branching operation of the optical fiber cable is improved.

According to the above aspect of the present invention, it is possible to stabilize the binding state of the binding material wound around the plurality of optical fibers in an SZ shape.

It is the schematic explaining the structure of the optical fiber unit which concerns on this embodiment. It is sectional drawing explaining the structure of the optical fiber cable provided with the optical fiber unit of FIG. It is the side view which looked at the binding apparatus from the radial direction. It is an A direction arrow directional view of FIG. 3A. It is a figure for demonstrating an overlap rate. It is the schematic explaining the structure of the optical fiber unit which concerns on a modification. It is the schematic explaining the structure of the optical fiber unit which concerns on another modification. It is an expanded view of the binding material of FIG. 6A.

The configuration of the optical fiber unit according to the present embodiment will be described below with reference to FIGS. 1 to 6B.
In addition, about the figure used for the following description, in order to make an invention easy to understand, illustration of each component is abbreviate | omitted, the change of a scale, the simplification of a shape, etc. may be carried out.

As shown in FIG. 1, the optical fiber unit 10 includes a plurality of optical fibers 1 and two binding materials 2 and 3 that bind the plurality of optical fibers 1.

(Direction definition)
As shown in FIG. 1, the plurality of optical fibers 1 are bundled in a cylindrical shape as a whole. In the present embodiment, the central axis of the cylinder is referred to as a central axis O. The direction in which the optical fiber unit 10 extends, that is, the direction along the central axis O is referred to as the longitudinal direction. The Z axis in FIGS. 1, 3A, 5, 6A, and 6B indicates the longitudinal direction. Further, in a front view viewed from the longitudinal direction, a direction intersecting the central axis O is referred to as a radial direction, and a direction around the central axis O is referred to as a circumferential direction.
The plurality of optical fibers 1 may be bundled in a columnar shape having a non-circular (elliptical, rectangular, etc.) cross section, and the cross-sectional shape thereof may change in the longitudinal direction. In this case, a virtual line connecting the centroids of the cross section of the optical fiber unit 10 in the longitudinal direction is defined as the central axis O.

As the plurality of optical fibers 1, for example, a bundle of a plurality of 12-fiber intermittently bonded optical fiber ribbons can be used.
The binding materials 2 and 3 are formed in a band shape. As the binding materials 2 and 3, for example, a combination of a plurality of fibers made of a high melting point material such as polyethylene terephthalate (PET) and a low melting point material such as polypropylene (PP) can be used. In addition, the structure and material of the binding materials 2 and 3 are not limited to the above, and can be changed as appropriate.

The binding materials 2 and 3 are wound around the plurality of optical fibers 1 in an SZ shape, and are bonded to each other at each reversal portion to form an adhesive portion B. The binding materials 2 and 3 are heat-bonded to each other at a bonding portion B by a binding device 20 described later. A plurality of optical fiber units 10 may be arranged in the optical fiber cable. In order to distinguish between the plurality of optical fiber units 10 in the optical fiber cable, the binding materials 2 and 3 may be colored differently.

The optical fiber unit 10 is used by being housed in, for example, an optical fiber cable 100 as shown in FIG.
The optical fiber cable 100 includes a plurality of optical fiber units 10, a wrapping tube 54, a cylindrical sheath 55, a pair of strength members 56, and a pair of tear strings 57.

The wrapping tube 54 covers the plurality of optical fiber units 10. The sheath 55 covers the optical fiber unit 10 together with the wrapping tube 54. The pair of strength members 56 are embedded in the sheath 55. The pair of tear strings 57 are embedded in the sheath 55. The pair of tear strings 57 are disposed at positions close to the inner peripheral surface of the sheath 55. Marker protrusions 58 project from the outer peripheral surface of the sheath 55 on the radially outer side of the position where the pair of tear strings 57 are disposed. The marker protrusion 58 is formed along the tear string 57 and indicates a position where the tear string 57 is embedded. Note that the optical fiber cable 100 may not include the wrapping tube 54, the tensile body 56, the tear string 57, and the marker protrusion 58. The optical fiber cable 100 may include only one optical fiber unit 10.

Next, a method for manufacturing the optical fiber unit 10 shown in FIG. 1 will be described.

The optical fiber unit 10 is formed by winding the binding materials 2 and 3 around a plurality of optical fibers 1 using a binding device 20 as shown in FIGS. 3A and 3B.
3A is a side view of the binding device 20 as viewed from a direction orthogonal to the longitudinal direction, and FIG. 3B is a view in the direction of arrow A in FIG. 3A.

As shown in FIGS. 3A and 3B, the bundling device 20 is composed of a plurality of cylindrical members. The bundling device 20 includes a guide cylinder 21, a first inner cylinder 22, a first outer cylinder 23, a second inner cylinder 24, and a second outer cylinder 25 in order from the inside. These members are arranged in a state where the respective central axes are located on the central axis O. A plurality of optical fibers 1 are inserted into the guide tube 21.

The first inner cylinder 22 is fitted in the first outer cylinder 23 so as to be rotatable around the central axis O with respect to the first outer cylinder 23. On the outer peripheral surface of the first inner cylinder 22, a groove portion 22a extending over the entire length in the longitudinal direction is formed. The binding material 2 is inserted into the groove 22a.
The second inner cylinder 24 is fitted in the second outer cylinder 25 so as to be rotatable around the central axis O with respect to the second outer cylinder 25. On the outer peripheral surface of the second inner cylinder 24, a groove portion 24a extending over the entire length in the longitudinal direction is formed. The binding material 3 is inserted into the groove 24a.

The first inner cylinder 22 and the second inner cylinder 24 are connected to a common power source (not shown), and are configured to rotate around the central axis O in conjunction with power supply. When the optical fiber unit 10 is formed, the bundling materials 2 and 3 in the groove portions 22a and 24a become the plurality of optical fibers 1 as the plurality of optical fibers 1 pass through the guide tube 21 and are drawn downstream. Wrapped in the SZ shape. In addition, since the binding materials 2 and 3 are respectively heated and partially melted in the groove portions 22a and 24a, they are heat-bonded to each other at the SZ-shaped reversal portion.
The binding materials 2 and 3 may not be heated in the groove portions 22a and 24a, but may be heated in a heating die (not shown) disposed downstream of the binding device 20. In this case, the binding materials 2 and 3 are heat-sealed in a heating die after leaving the binding device 20 while being wound around the plurality of optical fibers 1 in an SZ shape.

Next, specific examples of the optical fiber unit 10 of the present embodiment will be described.

In FIG. 1, C <b> 2 is the center line of the binding material 2, and C <b> 3 is the center line of the binding material 3. As shown in FIG. 1, the center lines C <b> 2 and C <b> 3 intersect twice in the binding material 2 and the inverted portion of the binding material 3. That is, the two binding materials 2 and 3 form an adhesive part B that is bonded to each other at each inverted part, and the adhesive part B includes a plurality of intersections between the center lines C2 and C3. Thus, the adhesive portion B includes two adhesive surfaces b1 and b2 where the binding materials 2 and 3 overlap each other. The bonding surfaces b1 and b2 are arranged with a gap in the longitudinal direction. The bonding surface b1 is located on the −Z side, and the bonding surface b2 is located on the + Z side. Further, a gap S between the binding materials 2 and 3 is formed between the bonding surface b1 and the bonding surface b2. The intersection point means a point where the center lines C2 and C3 intersect when the bonding portion B is viewed from the outside in the radial direction of the optical fiber unit 10.
Here, the length in the longitudinal direction of the bonding portion B is referred to as a bonding length L. The bonding length L is a distance in the longitudinal direction between the −Z side end of the bonding surface b1 and the + Z side end of the bonding surface b2. Moreover, as shown in FIG. 1, the binding pitch in the longitudinal direction of the binding materials 2 and 3 wound in the SZ shape is referred to as a binding pitch P. The binding pitch P is a unit in which the shape of the binding materials 2 and 3 in the longitudinal direction is repeated.
Further, as shown in FIG. 1, the distance in the longitudinal direction between the intersections A1 and A2 of the center lines C2 and C3 is referred to as a distance X between the intersections.

FIG. 5 is a diagram illustrating a modification of the optical fiber unit 10. In the example shown in FIG. 5, each of the binding materials 2 and 3 is inverted three times at the inversion portion. As a result, the bonding portion B includes four intersections A1 to A4 of the center lines C2 and C3. Further, the bonding portion B includes four bonding surfaces b1 to b4. The four bonding surfaces b1 to b4 are arranged at intervals in the longitudinal direction. Thereby, in the bonding part B, gaps S between the binding materials 2 and 3 are formed at three locations.
In addition, the frequency | count of reversing the binding materials 2 and 3 in one inversion part is not restricted to the example of FIG. 1, or the example of FIG. For example, when the binding materials 2 and 3 are reversed N times at the reversal part, the number of intersections of the center lines C2 and C3 is (N + 1).

As shown in FIG. 5, when there are three or more intersections of the center lines C <b> 2 and C <b> 3 in one bonding portion B, the average value of the distances in the longitudinal direction between the adjacent intersections is set as the distance X between the intersections. . In the example shown in FIG. 5, if the distances in the longitudinal direction between the intersection A1 and the intersection A2, the intersection A2 and the intersection A3, and the intersection A3 and the intersection A4 are X1, X2, and X3, respectively, the average value of X1 to X3 is It is defined as the distance X between intersections.
When there are three or more bonding surfaces in one bonding portion B, the bonding length L is the distance in the longitudinal direction between the outer ends of the bonding surfaces located at both ends in the longitudinal direction. . In the example shown in FIG. 5, the bonding surface b1 is positioned closest to the −Z side, and the bonding surface b4 is positioned closest to the + Z side. In this case, the distance in the longitudinal direction between the −Z side end of the bonding surface b1 and the + Z side end of the bonding surface b4 is defined as the bonding length L.

FIG. 4 is a front view of the optical fiber unit 10 as viewed from the longitudinal direction. In FIG. 4, the optical fiber 1 is not shown. As shown in FIGS. 1, 4, and 5, the reversing part of the binding material 2 covers the reversing part of the binding material 3 from the outside in the radial direction. That is, the inversion part of the binding material 2 and the inversion part of the binding material 3 overlap each other.
As shown in FIG. 4, the portion where the binding materials 2 and 3 overlap in the front view extends in the circumferential direction. An angle around the central axis O of the portion where the binding materials 2 and 3 overlap is defined as θ [°]. At this time, the overlap rate R [%] is defined by the following formula (1).
R = 100 + θ / 180 (1)

A plurality of optical fiber units 10 were created using the distance X between the intersections defined as described above, the bonding length L, the binding pitch P, and the overlap ratio R as parameters, and the results of measuring the strength and the like of the bonded portion are shown in Table 1. Shown in

　　　　　　　　　　　　　　　　　 

The optical fiber units of the comparative example and Examples 1 to 8 shown in Table 1 use six 12-fiber intermittently bonded optical fiber ribbons as the plurality of optical fibers 1. In addition, two binding materials 2 and 3 are wound in an SZ shape around the six intermittently bonded optical fiber ribbons, and the inversion portions of the binding materials 2 and 3 are heat-sealed to form an adhesive portion B. is doing. In the comparative examples and Examples 1 to 8, the binding materials 2 and 3 having a width of 1 [mm] by combining a plurality of fibers made of PET and PP are used.

In the comparative example shown in Table 1, the binding materials 2 and 3 are heat-sealed so that the center lines C2 and C3 of the binding materials 2 and 3 intersect at one point. Since the center lines C of the binding materials 2 and 3 intersect at one point, the distance X between the intersections is 0 [mm], but the binding materials 2 and 3 have a width of 1 [mm]. The adhesion length L is 8 [mm].
On the other hand, for example, in Example 1, the center lines C2 and C3 of the binding materials 2 and 3 have two intersections as shown in FIG. 1, and the distance X between the intersections is 8 [mm]. The length L is 18 [mm] which is 10 [mm] longer than the comparative example.
For example, in Example 7, the center lines C2 and C3 of the binding materials 2 and 3 have four intersections as shown in FIG. 4, the distance X between the intersections is 17 [mm], and the bonding length L Is 75 [mm].
Example 8 is an optical fiber unit in which the binding materials 2 and 3 are each inverted five times at the reversing part so that there are six intersections of the center lines C2 and C3 per adhesive part B.

L / P shown in Table 1 is a value obtained by dividing the adhesive length L [mm] by the binding pitch P [mm]. For example, in Example 1, since the adhesion length L = 18 [mm] and the binding pitch P = 150 [mm], L / P = 18/150 = 0.12.

L / (P / 2) shown in Table 1 indicates the ratio of the length of the bonded portion B to the length of the optical fiber unit 10 in the longitudinal direction. More specifically, as shown in FIG. 1, when there are two binding materials, there are two bonding portions B per binding pitch P. For this reason, the numerical value obtained by dividing the bonding length L by P / 2 is the ratio of the length of the bonding portion B to the length of the optical fiber unit 10 in the longitudinal direction. For example, in Example 1, L / (P / 2) = 18 / (150/2) = 0.24.

The adhesive strength [gf] shown in Table 1 is the tensile force when the binding materials 2 and 3 are pulled apart at a speed of 200 [mm / min] in the circumferential direction in the bonding portion B, and the bonding portion B is peeled off. Is the peak value.

The loss [dB / km] after cable formation shown in Table 1 is obtained by using the optical fiber unit 10 of the comparative example and Examples 1 to 8 to produce the optical fiber cable 100 as shown in FIG. It is the result of measuring the maximum value of the transmission loss of the optical fiber 1 at 55 [μm].
In addition, Table 1 shows the number and probability [%] that the bonded portion B is broken (peeled or bonded poorly) per 3 [m] when the optical fiber unit 10 is taken out from the optical fiber cable 100. Yes. For example, when the number of binding materials is two and the binding pitch P is 150 [mm], the bonding portion B is included at a rate of one in 75 [mm]. ÷ 75 = 40 bonding portions B are included. In the comparative example, since all of the 40 bonded portions B were confirmed to be broken, the probability that the bonded portion B was broken per 3 [m] was 100 [%].

In Example 1, the number of bonded portions B destroyed per 3 [m] is greatly reduced from 40 to 0 in comparison with the comparative example. This is because the adhesive strength is improved from 4.0 [gf] to 20.1 [gf], and the bonded portion B is not easily broken. The reason why the adhesive strength is increased is that the number of intersections of the center lines C2 and C3 per adhesive part B increases from one to two, and the value of L / (P / 2) indicating the ratio of the adhesive part B Is increased from 0.11 to 0.24.
Thus, by increasing the number of intersections of the center lines C2 and C3 and increasing the value of L / (P / 2) and the adhesive strength, it is possible to reduce the probability that the bonded portion B is broken. .

Next, the optimum numerical range of L / (P / 2) will be considered.
Focusing on the numerical value of L / (P / 2) for the comparative example and examples 1 to 8, the minimum value is 0.11 of the comparative example, and the next smaller value is 0.24 of the example 1. Yes. The probability that the bonded portion B is broken around 3 [m] is 100% in the comparative example and 0% in the example 1. From this result, the optimum value of L / (P / 2) for preventing the fracture of the bonded portion B is in the range shown in the following mathematical formula (2).
0.24 ≦ L / (P / 2) (2)

On the other hand, when the value of L / (P / 2) is large, when the binding materials 2 and 3 are wound around the plurality of optical fibers 1 in the SZ shape, the binding materials 2 and 3 are attached after the bonding portion B is formed. The distance or time in the longitudinal direction until inversion is shortened. For this reason, it becomes easy to generate | occur | produce the adhesion defect in the adhesion part B of the binding materials 2 and 3. FIG. Therefore, it is desirable to set a small value as L / (P / 2).
For example, in the example shown in Table 1, in Example 5 where the value of L / (P / 2) is 0.93, since the value of L / (P / 2) is large, the bonding failure of the binding materials 2 and 3 is caused. As a result of the occurrence, it is considered that the bonded portion B was destroyed with a probability of 10%. In addition, the value of L / (P / 2) next to Example 5 was 0.80 of Example 4, but in Example 4, no breakage of the bonded portion B was confirmed. From this result, it is more preferable that the value of L / (P / 2) is in the range shown in the following mathematical formula (3).
L / (P / 2) ≦ 0.8 (3)

From the above consideration and formulas (2) and (3), it can be said that the value of L / (P / 2) is optimally set in the range shown in the following formula (4).
0.24 ≦ L / (P / 2) ≦ 0.8 (4)

Next, the optimum numerical range of the adhesive strength will be considered.
Focusing on the numerical values of the adhesive strengths for the comparative example and examples 1 to 8, the minimum value is 4.0 [gf] of the comparative example, and the next smaller value is 11.6 [gf] of the example 5. . In addition, the probability that the bonded portion B was broken around 3 [m] was 10% in Example 5 with respect to 100% in the comparative example, which is greatly improved. From this, by setting the adhesive strength to 11.6 [gf] or more, it is possible to prevent the bonding portion B from being broken to some extent.
In addition, the adhesive strength next to that of Example 5 is 19.5 [gf] of Example 4, and the probability that the adhesive part B is broken around 3 [m] in Example 4 is 0%. It has become. From this, by making the adhesive strength 19.5 [gf] or more, it is possible to more reliably prevent the bonded portion B from being broken.

On the other hand, when the value of the adhesive strength is too large, it is considered that the binding materials 2 and 3 are difficult to peel off at the bonding portion B, and therefore it is difficult to perform the branching operation after the intermediate. The optical fiber unit 10 was taken out from the optical fiber cables 100 of Examples 1 to 8, and workability when the binding materials 2 and 3 were peeled off at the bonding portion B was confirmed. As a result, in Example 8 having the largest adhesive strength of 95.2 [gf], the workability of the work of separating the binding materials 2 and 3 was not deteriorated. From this result, it is preferable to set the adhesive strength to 95.2 gf or less in order not to deteriorate the workability when peeling the bonded portion B.

Therefore, a preferable condition for maintaining the separation work of the binding materials 2 and 3 easily in the adhesive portion B while preventing the adhesive portion B from being unexpectedly broken is that the adhesive strength is 11.6 gf or more and 95.2 gf. It is the following. In addition, when the adhesive strength is 19.5 [gf] or more, the breakage of the bonded portion B can be prevented more reliably.

Next, the optimum numerical range of the overlap rate R will be considered.
The condition for the center lines C2 and C3 of the binding materials 2 and 3 to have a plurality of intersections at the bonding portion B is that θ in FIG. 4 is greater than 0 [°]. Further, from the definition of the overlap rate R shown in Equation (1), when θ is greater than 0 [°], the overlap rate R is greater than 100 [%]. That is, the optical fiber unit 10 can be configured so that the center lines C2 and C3 of the binding materials 2 and 3 have a plurality of intersections at the bonding portion B by making the overlap rate R larger than 100 [%]. it can.

When the binding materials 2 and 3 are wound in an SZ shape, it is common to define the winding shape of the binding materials 2 and 3 so that the center lines C2 and C3 each have a sine curve. Here, when θ in FIG. 4 exceeds 45 [°], that is, when the overlap rate R exceeds 125%, the center lines C2 and C3 intersect at an angle close to a right angle at the intersections A1 and A2. When the center lines C2 and C3 intersect at an angle close to a right angle, the areas of the bonding surfaces b1 and b2 become relatively small.
Therefore, by setting the overlap rate R to 125% or less, it is possible to secure the areas of the adhesive surfaces b1 and b2 and improve the adhesive strength.

Next, the optimal numerical range of the inter-intersection distance X is considered.
When the distance X between the intersections is too small, the formation of the intersections A1 and A2 of the center lines C2 and C3 is likely to be unstable, and the shapes of the bonding surfaces b1 and b2 are likely to be unstable. As a result, the adhesive strength also becomes unstable. For this reason, it is desirable that the distance X between the intersections is, for example, 33 mm or more.
Moreover, when the distance X between intersections is too large, the ease of discriminating between the plurality of optical fiber units 10 by the binding materials 2 and 3 decreases. For this reason, it is desirable that the distance X between the intersections is, for example, 59 mm or less.

The optimum values of L / (P / 2), adhesive strength, overlap rate R, and intersection distance X described above are merely examples of preferred embodiments of the present invention, and the technology of the present invention. The target range is not limited to this numerical range.

As described above, according to the optical fiber unit 10 of the present embodiment, the plurality of binding materials 2 and 3 are wound around the plurality of optical fibers 1 in an SZ shape. A plurality of intersections A1 and A2 between the center lines C2 and C3 of the binding materials 2 and 3 are included in the bonding portion B where the inverted portions of the binding materials 2 and 3 are bonded to each other. With this configuration, when the optical fiber unit 10 is manufactured, even if, for example, the positions where the reversal portions of the binding materials 2 and 3 are formed and the shapes of the reversal portions vary, the bonding portion B can be securely attached. It becomes possible to form. Therefore, the binding state of the binding materials 2 and 3 can be stabilized.

Further, for example, when a force that separates the binding materials 2 and 3 acts on the entire bonding portion B, the external force can be received by the entire bonding surfaces b1 and b2 formed at intervals in the longitudinal direction. For this reason, it can suppress that the adhesion parts b1 and b2 peel off unexpectedly. On the other hand, when the optical fiber 1 is taken out by peeling the adhesive portions b1 and b2, the adhesive surface b1 can be easily peeled off by concentrating the force that separates the binding materials 2 and 3 on the single adhesive surface b1, for example. Can be made. Then, by sequentially peeling the bonding surfaces b1 and b2 along the longitudinal direction, it is possible to peel the bonding portion B with a small operation force, and the intermediate post-branching operation can be facilitated.

Further, since the gap S between the binding materials 2 and 3 is formed between the bonding surfaces b1 and b2, for example, the positions where the inverted portions of the binding materials 2 and 3 are formed and the shapes of the inverted portions vary. Even if it is a case, it is suppressed that the area of the bonding surfaces b1 and b2 varies greatly. Thereby, at the time of manufacture of optical fiber unit 10, the adhesive strength of adhesion part B can be stabilized easily.

In addition, as shown in FIG. 5, when the bonding portion B includes four or more intersections between the center lines C2 and C3 of the binding materials 2 and 3, the length in the longitudinal direction of the bonding portion B is ensured. Thus, the binding state of the binding materials 2 and 3 can be further stabilized.

Moreover, when the value of L / (P / 2) is 0.24 or more, the length in the longitudinal direction of the bonding portion B occupying the entire binding materials 2 and 3 is secured, and the bonding portion B is unexpectedly moved. Peeling can be prevented. Furthermore, when the value of L / (P / 2) is 0.8 or less, when the optical fiber unit 10 is manufactured, the length from when the bonding portion B is formed to when the binding materials 2 and 3 are reversed Occurrence of poor adhesion due to a short distance or time in the direction can be suppressed.

Moreover, when the adhesive strength of the adhesive part B is 11.6 gf or more, it is possible to prevent the adhesive part B from being unexpectedly peeled off. Furthermore, when the bonding part B is set to 95.2 gf or less, workability when the binding materials 2 and 3 are peeled from each other in the bonding part B can be improved.

Further, by making the overlap ratio of the binding materials 2 and 3 larger than 100%, the bonding surfaces b1 and b2 between the binding materials 2 and 3 can be surely formed and the binding state can be stabilized. Furthermore, by setting the overlap ratio to 125% or less, it is possible to secure the areas of the bonding surfaces b1 and b2 and increase the bonding strength.

Further, according to the optical fiber cable 100 of this embodiment, the binding materials 2 and 3 are wound around the plurality of optical fibers 1 in an SZ shape, and the binding state of the binding materials 2 and 3 is stable. With this configuration, it is possible to secure the discriminability of the optical fiber unit 10 while suppressing the bundle of optical fibers 1 from being separated, and to improve the workability of the optical fiber cable 100 such as an intermediate post branching operation.

The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, in the above embodiment, the binding materials 2 and 3 are heat-sealed to form the bonding surfaces b1 to b4, but the present invention is not limited to this. For example, the bonding surfaces b1 to b4 may be formed by bonding the binding materials 2 and 3 with an adhesive.

Moreover, in the said embodiment, although the optical fiber unit 10 was provided with the two binding materials 2 and 3, this invention is not restricted to this, For example, the optical fiber unit 10 provided with three or more binding materials is employ | adopted. Also good. For example, FIG. 6A shows a case where four binding materials 4, 5, 6, and 7 are wound around a plurality of optical fibers 1 in an SZ shape. When the binding materials 4, 5, 6, and 7 in FIG. 6A are developed on a plane, the result is as shown in FIG. 6B.
As shown in FIG. 6A, even when there are more than two binding materials wound in the SZ shape, the bonding length L and the binding pitch P are defined as in the case of two binding materials. Accordingly, even when three or more binding materials are wound in an SZ shape, the optical fiber unit 10 is configured so as to satisfy 0.24 ≦ L / (P / 2) ≦ 0.8. It is possible to prevent B from peeling off unexpectedly, and to suppress the occurrence of poor adhesion of the binding materials 2 and 3 during manufacturing.

In addition, it is possible to appropriately replace the constituent elements in the above-described embodiments with well-known constituent elements without departing from the spirit of the present invention, and the above-described embodiments and modifications may be appropriately combined.

DESCRIPTION OF SYMBOLS 1 ... Optical fiber 10 ... Optical fiber unit 2, 3 ... Bundling material 100 ... Optical fiber cable C2, C3 ... Center line A1, A2, A3, A4 ... Intersection B ... Adhesion part b1, b2, b3, b4 ... Adhesion surface L ... Adhesion length O ... Center axis P ... Binding pitch S ... Gap

Claims (8)

1. A plurality of optical fibers;
   An optical fiber unit comprising at least two binding materials for binding a plurality of the optical fibers,
   The two binding materials are wound around the plurality of optical fibers in an SZ shape, and form an adhesive portion that is bonded to each other at each reversal portion,
   The optical fiber unit, wherein the bonding portion includes a plurality of intersections between the center lines of the two binding materials.
2. The adhesive portion includes a plurality of adhesive surfaces on which the binding materials overlap each other, and the plurality of adhesive surfaces are arranged at intervals in a longitudinal direction in which the optical fiber unit extends. Fiber optic unit.
3. The optical fiber unit according to claim 2, wherein a gap is formed between the plurality of bonding surfaces and between the two binding materials.
4. The optical fiber unit according to any one of claims 1 to 3, wherein the adhesive portion includes four or more intersections between the center lines of the two binding materials.
5. An adhesive length L of the adhesive portion in the longitudinal direction of the optical fiber;
   The binding pitch P of the binding material in the longitudinal direction is
   5. The optical fiber unit according to claim 1, wherein 0.24 ≦ L / (P / 2) ≦ 0.8 is satisfied.
6. The optical fiber unit according to any one of claims 1 to 5, wherein an adhesive strength of the adhesive portion is 11.6 gf or more and 95.2 gf or less.
7. The optical fiber unit according to any one of claims 1 to 6, wherein an overlap ratio of the two binding materials is greater than 100% and equal to or less than 125%.
8. The optical fiber unit according to any one of claims 1 to 7,
   A sheath covering the optical fiber unit;
   An optical fiber cable comprising:

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